Ground Source Heat pumps

Ground source heat pumps use renewable energy in a new, clean way to provide heating to an increasing number of properties. GSHPs use renewable energy located in the ground and recognised as one of the most energy efficient ways of providing heat within a range of properties. Ground source heat pumps can be used in wide amount of buildings and are particularly suitable for projects where a low environmental impact if required.

How do ground source heat pumps work?

A heat pump works in a similar way to a refrigerator but uses the 'hot end' of the process. In a refrigerator, heat is obtained from inside the fridge and moved to the rear where the pipe work can be seen. A heat pump can create heat from a range of energy sources. It can uses solar energy stored in the ground, air or water and convert it to a higher temperature which can then be transferred to be used in a heating system such as under floor heating.

A heat pump system consists of three main components:

Heat source

Heat pump

Heat distribution system

Ground source heat pumps use a loop buried in the ground which contains a mixture of water and antifreeze. The ground loop liquid is circulated and absorbs the heat from the ground to be used by the heat pump. This heat is then transferred to be used to heat radiators or underfloor heating systems.

The ground loop length varies dependant on the size of your home and the amount of heat you require. As one would expect; the longer the loop, the more heat that can be drawn from the ground by the heat pump.
Ideally, the ground loop would be coiled and put in a trench flat at approximately two metres deep. However, there are alternatives, for e.g. a vertical loop could be buried to a depth of around 100m or a slinky coil system could be used. Contact a ground source heat pump specialist to discuss specific installations.

Ground source heat pump (GSHP) benefits:

A ground source heat pump could save approx 500kg of carbon dioxide emissions every year if for example it replaces an oil boiler.

Ground source heat pumps only use electricity to provide the heat for your home so no other heating fuel would be required

Heating your home with a ground source heat pump is much more efficient than using many other forms of fuels and systems.

Costs and savings of a ground source heat pump (GSHP):

Ground Source Heat Pump systems only use electricity to power the heat pumps. On average, a Ground Source Heat Pump will create 3 or 4 times the amount of thermal energy (heat) than electricity used to power the system. Green electricity can be purchased due to lower the environmental impact even further.

For under floor heating

(flow temperatures at 35°C)

36% cheaper than gas heating

56% cheaper than oil heating

58% cheaper than LPG heating

75% cheaper than electrical storage heating

For radiators

(flow temperatures at 45°C)

16% cheaper than gas heating

42% cheaper than oil heating

44% cheaper than LPG heating

67% cheaper than electrical storage heating

For hot tap water production

(flow temperature at 50°C)

2% more expensive than gas heating

29% cheaper than oil heating

32% cheaper than LPG heating

59% cheaper than electrical storage heating

The above were calculated using 'typical' energy prices on an average night and day tariff assuming a heat pump performance in line with the most efficient on the market. These assumptions are given as a guide and should only be used for this purpose.

How Much Will Ground Source Heat Pumps Cost to Install?

This depends on the size of your property and whether or not bore holes will need to be drilled to accommodate the coils, but as a rough guide, somewhere between £7,000 - £13,000.

How Much Heat Will Ground Source Heat Pumps Produce?

An “average” house, if there is such a thing, uses around 23,000 kWh of heat per year for heating, cooking and hot water and a good quality heat pump in a well insulated home should be able to produce all of this.

Is the Heat Produced by Ground Source Heat Pumps “Free”?

The pump is powered by electricity which of course needs to be paid for. The manufacturers claim that ground source heat pumps can produce around 4 kWh of heat for every 1 kWh of electricity used, though electricity is much more expensive than gas. At the time of writing this article, gas prices were at around 4p per kWh and electricity was at around 13.5p.

Will Ground Source Heat Pumps Only Produce Heat in Summer?

No, the temperature of the soil underground remains more or less constant throughout the year and so seasonal changes in weather should not affect the efficiency of a ground source heat pump. As with any heating system however it will obviously have to work harder in the colder months.

Could I Get a Grant Toward the Installation Cost?

Government grants are no longer available, having been replaced by the renewable heat incentive; however some energy companies may give grants. Your chosen installer should have the most up to date information and you are advised to check with them.